Study On Key Problems Of Cable-Stayed Bridge PC Pylon

In recent years, a large number of super-long span cable-stayed bridges appeared in China. Due to the request of structure function, more and more tendons with great curvature and massive tonnage are used in concrete construction. Because of the increment of span, in the design of pylon of super-long span cable-stayed bridge, the designed tonnage of cables achieves"kiloton"grade. And then the stress in the anchorage zone of pylons becomes greater and greater, there is no doubt that lots of new problems come forth in design.Moreover, because of the cable-stayed bridge pylon belong to the towering structure. It is in the formidable natural condition, such as the sun radiation varing with time. Besides, the complexity and uncetainties of the concrete material itself influence the short-term and long-term behavior of the pylon in a certain degree.These are all urgent topics that needs to be solved.1. Study on force-elongation relationship of small curvature tendonsIn allusion to the phenomenon of the deviation of measured elongation from calculated one, all kinds of factors influencing the elongation of tendon are involved in this paper. According to the squeeze effect caused by the equivalent radial load of them, the friction coefficient is modified. Besides, considered the tendon realignment made by strand effect and the radial deformation under the equivalent radial load, the calculation method of elongation for small curvature tendons is presented. Finally, the method is checked out through lots of measured elongation on site. Moreover, the elongations in the anchorage zone of Wuhekou cable-stayed bridge pylon are statistically analyzed.2. Full-scale segment model test on wuhekou cable-stayed bridge pylon The segment heighth, position, load method and the layout of sensors in cable-stayed bridge pylon segment experiment of literatures are compared in this paper. And the working behavior of all these segments are synopitically summarized. Moreover, through the comparision of the result of the segment experiment and that of the FEM analysis, the coefficients of safety against cracking and ultimate bearing capacity of anchorage zone of Wuhekou cable-stayed bridge pylon are studied. Besides, some suggestion is also proposed for the design of it. Finally, some new conclusions are expected by summarizing some segment experiments of cable-stayed bridge pylons in literatures.3. Entirely analysis of the anchorage zone of wuhekou cable-stayed bridge pylon Through the comparision of the therotical result of the segment and the whole pylon model, the coefficients of safety against cracking and working behavior of them are researched. And then, whether the behavior of the segment represents the pylon is confirmed. Moreover, the decay of the prestressed effect of tendon and that of the cable force along the pylon in the segment are analysized. At last, the results are compared with the decay of the prestressed effect of tendon and that of the cable force along the pylon in the whole pylon model.4. Study on the proper layout of tendons in the cable-stayed bridge pylon and optimal placement Based on the comparision of the segment experiments of three long span cable-stayed bridges, the proper layout of tendons in the cross-section of anchorage zone is studied. Moreover, the proper vertical distance of tendons is also analysised. At same time, by the linear programming and linear superposition...